According to the Duvergerian theories, only viable parties would beexpected to stand for elections alone in the long run, whereas nonviableparties would be thought to join a pre-electoral coalition withanother party or to withdraw from competition altogether. However,non-viable political parties throughout the world have been shown tocontinue presenting candidacies, calling into question the Duvergeriantheories. Developing from this apparent paradox, I argue that it is theoverlap of electoral arenas that generates opportunities for viableparties to present candidacies in arenas where they are non-viable.Through in-depth interviews with political leaders in Canada andSpain, I show that the overlap of electoral arenas turns the decision topresent candidacies when non-viable into the dominant strategy,whereas coalescing or withdrawing becomes the least favouredalternatives. This situation leads to an extra supply of parties competingto what the Duvergerian theories predict. Through a cross-nationalquantitative analysis with data from 46 countries, I address theinstitutional and the sociological determinants that account for variationin the number of parties competing, even if non-viable.